Abstract
Bacillus larvae, a pathogen of larval honey-bee, produces during sporulation either in the host or in culture a mixture of highly active proteases. They hydrolyse azoalbumin optimally at p H 6·6 and 60°C and retain over 80 per cent activity after 30 minutes' incubation. The proteolytic activity is inhibited by EDTA and Zn 2+ but not by crystalline soybean trypsin inhibitor or diisopropylfluorophosphoridate. The activity is restored by Co 2+ and Cu 2+ but not by Fe 2+, Mn 2+, Mg 2+, or Ca 2+. Three proteases are resolved by chromatographic and electrophoretic techniques. Two enzymes are extractable from the infected hosts and sporulated cultures and one from the vegetative cells of B. larvae. One enzyme with acidic p H optimum is found to be heat-stable while another with slightly alkaline p H optimum is heat-labile. Insensitivity to trichloroacetic acid precipitation and low sedimentation values suggest the enzymes to be of low molecular weight.
Published Version
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